Santhakumari, N C; Vallabhan, C P G(Elsevier, May , 1992)
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Abstract:
D.C. and a.c. electrical conductivities, dielectric constant and dielectric loss factor in single crystals of ethylenediammonium sulphate, (H3NCH2CH2NH3)(SO4), have been measured axiswise as a function of temperature. Anomalous variations in all the above properties at 480 K indicate the occurrence of a phase transition in the above material at this temperature. The existence of such a phase transition is also confirmed by DSC measurements. Electrical conductivity results are analysed and the activation energies of conduction at different temperature regions have been evaluated from the logσ vs 103T−1 plot. Possible mechanisms for the electrical conduction process are discussed, the available results being in favour of a proton transport model.
Bindu, G; Vinu, Thomas; Anil, Lonappan; Aanandan,C K; Mathew, K T(John Wiley & Sons, January , 2006)
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Abstract:
A phantom that exhibits complex dielectric properties similar to low-water-content biological tissues over the electromagnetic spectrum of 2000–3000 MHz has been synthesized from carbon black, graphite powder, and poly vinyl acetate (PVA)-based adhesive. The material overcomes various problems that are inherent in conventional phantoms such as decomposition and deterioration due to the invasion of bacteria or mold. The absorption coefficients of the material for various concentrations of carbon and graphite are studied. A combination of 50% poly-vinyl-acetate-based adhesive, 20% carbon, and 30% graphite exhibits a high absorption coefficient, which suggests another application of the material as a good microwave absorber for the interior lining of tomographic chamber in microwave imaging. The cavity-perturbation technique is adopted to study the dielectric properties of the material.
Anantharaman, M R; Joy, P A; Sagar, S(Taylor & Francis, March 13, 2009)
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Abstract:
Here we report the multiferroic nature of charge ordered manganite Gd0.5Sr0.5MnO3 for
the first time. The temperature variation of dielectric constant shows broad relaxor type
ferroelectric transition at around 210K and magnetization measurements shows weak
ferromagnetism at 50K. The dielectric peak is very close to charge ordering temperature
which is an evidence of the link between electronic state and increase of dielectric
response. Butterfly variation of capacitance with voltage confirms ferroelectric nature
of the sample at room temperature